car's owner at gunpoint for some time. then later releasing the person unharmed. police followed the car to watertown. the suspects apparently threw explosive devices from the car. at some point during the standoff, they had at least one pressure cooker bomb similar to the ones used at the marathon finish line in boston. one suspect was killed in the shootout. again, the one in the black hat. he was reportedly run over when police approached his body. they discovered an ied strapped to his chest. these individuals were certainly planning on delivering more carnage in their paths, wherever they were going. witnesses reported hearing explosions and a massive gun battle that you can hear in this video between the two suspects and police. here's what adam, who had gunshots come through his window, told us not long ago. >> i went to the window, and

right outside of our apartment there were two shooters in between a sedan and a black mercedes-benz suv. they were in between these two cars taking cover behind the black suv, shooting down our street, which is laurel street. they were shooting westward, which looked to be about six to ten watertown police army vehicles. they were shooting about what seemed to be 70 to 80 yards down the street utilizing handguns. while they were engaging in gunfire, they were also using explosives. it looked to resemble a pressure cooker, from what i've seen from other pictures online in the last few days. i saw them light this bomb. they threw it towards the officers, and it only got maybe 15 to 20 yards down, so it wasn't very close to the officers, but it really created a significant decoy. there was smoke that covered our

entire street. at that point, one of the shooters ran towards the officers while still engaging in gunfire. while he was still shooting at them, a few seconds later, the second shooter got back into the suv and turned it around and went full speed into the police officers. >> all right. police say other unexploded explosives have been left behind. officials tell nbc news the two suspects in the marathon bomb having international ties, may have military experience, and appear to have been in the u.s. for as long as a year. again, one of the suspects, the one in the white hat, remains at large at this point. we're going to turn now to nbc's michael leiter. he's a terrorism analyst. he's joining us now from washington, d.c. michael, just from what we've heard as it unfolded all night

long, complete chaos still in some areas, especially in watertown, massachusetts, where a suspect is still at large and clearly extremely dangerous. but the latest information about the suspects, what does that tell you? >> well, it tells me that honestly these guys probably don't lack the sophistication that people started imagining when we were just talking about the pressure cooker bomb. it was very, very simple and not much to it. they had obviously planned a lot out. i think that's how the fbi and boston authorities had been approaching this. although they now thought they recognized two, who knows how dangerous they could be, what else they could have set up, improvised explosive devices on their body they were carrying. this shows these two had thought a lot about this for a long time. we saw some of that planning with the precise placing of the bombs right there at the finish line. >> yeah, the brazenness and just

pure sickness of their actions. even from video at the bombing showing them literally looking at the scene, the carnage as it unfolded instead of running away from it. also, possibly any signs here from what we've heard in our reporting that they have been planning this for quite some time and this isn't some sort of random act that was pulled together at the last minute. >> that's right. and i'm going to try not to make the mistake that others have made in this investigation, to prejudge and get out ahead of the facts. what we know is we've got one dead and one very, very dangerous individual still out there. whether they have links to others, even that, i think the investigators don't know. i think they probably think it's these two, but do they have support from other people here or elsewhere? where else might they have ieds? again, they're going to keep

this very, very broad and try to narrow in on this one individual. >> all right. if you could stand by, we're going to go to watertown right now and just updating. these law enforcement officials say the activity overnight they have been dealing with, including the killing of one of the two suspects in the boston marathon bombing, they are directly related to the bombing. the two suspects have military experience and appear to have been in the u.s. for as long as a year, officials tell nbc news. and may have international ties. with that information, joining us now from watertown, massachusetts, is michael isikoff, who's there on the scene. michael, what can you tell us? >> reporter: well, these are two cold-blooded terrorists, in the words of police. we saw a pretty brazen example

of that tonight. here's the sequence of events as we understand them right now. at about 10:20 last night, there's a robbery at a 7-eleven in cambridge. after that, an m.i.t. police officer was shot and killed in his head. at that point, the two suspects who are the suspects in the boston marathon bombing, engage in a carjacking and seize a black mercedes suv. the victim in that case, the owner of the vehicle, is kept with them for about a half an hour while they drive through and head towards watertown chased by police. at some point, they let the victim out, and the police chase ensues to watertown at which point there's this fire fight. explosive devices are thrown from the car. one of the suspects is -- an

mbta transit officer is wounded seriously. one of the suspects is critically injured, taken into custody and is now dead. the other, the man with the white baseball cap, suspect number two in the boston marathon bombing, escapes. now, there's some indications that police may be aware of where he is. we see some police activity just down the road from us here, an indication that they are concentrating on one building, an office complex not just a couple blocks from where we are now. we don't know if the suspect is there. there seems to be some suspicion he's there. it may be they have him surrounded at this point. we're waiting to hear that and learn that shortly. >> michael isikoff, we'll check back in with you. at the end of the chase,

authorities of course shot and killed one of the suspects. he was run over. as they approached his body, they discovered an ied strapped to his chest. police say the streets are littered with unexploded devices and that depending on their ability to render them safe and to arrest the second suspect, authorities may freeze transit and lock down the town of watertown and adjoining areas until they find him. this guy is extremely dangerous. joining us now on the phone, former philadelphia police chief john timinney. what does this tell you about the suspects? especially the latest information that they may have international ties and have been in the u.s. for as long as a year? >> well, it's quite unusual. usually these terrorists, suicide bombers, they go out

with the bomb itself or they usually hit with a detonated device and flee the area. these two guys obviously detonated the bombs but then hung in the area for four extra days. what happened last night when the fbi released the pictures is reminiscent of what happened in d.c. during the sniper case back in 2002. in this case, the car. in this case, the pictures were released. within six hours, the bad guys are spotted. one officer gets killed at m.i.t. that begins a whole series of events culminating in the killing of terrorist number one. now it looks like they may have located the second guy. but these guys present a tremendous problem in that they're willing to go out in a ball of fire. the second person still may have some ieds on him or nearby or

setting a booby trap. so this is a real, real difficult situation. already one cop has been killed, another seriously injured. so the police, by necessary for their own protection, but also for the protection of the people in that small town, have got to move methodically. the best thing people can do is stay in their homes, shelter in place until this whole thing is over. >> so what -- just given what we know -- and in a sense, i'd love to know what your call would be given what we know. but locking down an entire town and adjoining areas, how is that done? clearly, police paneand fbi age and everybody involved here have to find this guy. they're driven not only by the necessity of what happened at the boston marathon but the necessity of the moment, having lost one of their own, which will drive them even further to make sure they get him. but how, chief timoney, how do you lock down an entire swath of land? >> well, i mean, i've been involved in situations like this. so usually what you're going to

do is use loud speakers. especially when daylight hours come. my sense is everybody is awake in that neighborhood. you had the young student on before where a bullet went through his bedroom window and almost hit him. the people in that neighborhood are aware. the police are just re-enforcing. i can guarantee they're watching msnbc, they're watching other television, listening to radios. they're getting the message to stay indoors. the only thing they can do by coming outdoors would be to complicate matters. we saw one gentleman earlier, obviously an innocent guy, who wound up having the police handcuff him because you don't know who you're dealing with or who's the real person, who's the person they're looking for. these are extremely fast-moving, dynamic situations. what police need at this time is for full cooperation where there aren't extra people out on the street, they stay in their homes, out of danger, and allow the police to methodically comb the neighborhood.

and it sounds like from michael isikoff's report, they may have somebody, or suspect to have somebody in an office complex nearby. >> they know who he is at this point. the case is solved in terms of the who. but let me ask you this, given the fact that the suspect who perished had an ied strapped to his chest and the streets apparently are littered with bombs and unexplode devid devic. are there possibilities here that there are others involved and not just these two working together? >> it could be. you leave all options open. there may be more involved. these may be just the two. you've got to take it one step at a time and assume the next guy they're looking for now has access to guns, has access to ieds. don't think for a second -- police officers are trained all the time. when you arrest somebody, you

get the first gun, and you continue to search for the second gun. the same rule will apply here. they'll continue to search until they're satisfied that there's no more than these two individuals. >> again, watertown, massachusetts, is ground zero now for the search for the second suspect in the boston marathon bombing. chief timoney, can you hear me? i think he just hung up. that's okay. we'll get him back. again, the two suspects in the boston marathon bombing are now down to one. one perished in a fire fight with police. they actually ran over his body, found his body with an ied strapped to his chest. there was a chase from cambridge where they carjacked somebody, let the person go, all the way to the watertown, massachusetts, as they were throwing bombs out of their car. a massive shootout throughout the night in watertown frightened the neighborhood. the neighborhood terrorized at this point because police are telling them the other suspect, who is still on the loose, is

armed and extremely dangerous. they have proven so time and time again since the bombing in boston on monday. we have a statement from m.i.t. an m.i.t. police officer was shot and killed in the line of duty. this happened last night. they say, our thoughts are now with the family. around 2:00 a.m., m.i.t. police determined that the suspect was no longer on campus and that it is safe to resume normal activities. however, m.i.t. police ask that members of their community remain vigilant in the coming hours. m.i.t. is heartbroken by the news that an m.i.t. police officer was shot and killed in the line of duty on thursday night, late last night near building 32 on campus. that, of course, is due to the two suspects who started their rampage there as they were trying to elude police and authorities in light of what they did at the boston marathon, at the finish line of the boston marathon. the fbi and all law enforcement

authorities have been culling through pictures. these are them. the man in the white cap is still on the loose as they still continue to elude police. one suspect dead. the suspect on the run in watertown. the latest out of watertown, massachusetts, is that the fbi and police and law enforcement authorities are at this point considering locking down the entire community and adjoining areas and also literally freezing mass transit so they can completely encompass the area and find this guy. here is a sound bite from a witness who watched what happened in watertown as his streets filled with bombs and gunfire through the night. this is andrew. >> i went to the window, and right outside of our apartment there were two shooters in between a sedan and a black mercedes-benz, suv. they were in between these two cars taking cover behind the

black, suv, shooting down our street, which is laurel street, and they were shooting westward -- >> all right. this is a briefing right now taking place. let's listen in. massachusetts state police. >> -- all public transportation service on the mbta system, that is buses and subway. so all public transit services through the mbta have been meetly suspended. we are hoping that as we proceed through the next number of hours that we will be able to turn back on portions of the system, but the system has been shut down now as a safety measure. people that are at subway stations or bus stops, we are asking them to go home. we do not want people congregatcongregat congregating and waiting for the system to come back on. so we're asking people, do not go out to the bus stations, subway stations.

if you're there, please go home. we also want to speak to the residents and the public within the town of watertown and the cities and towns that are abutting watertown and to be specific we are speaking to the residents of watertown, newton, waltham, belmont, cambridge, and the austin brighton neighborhoods of boston. to those people, we are asking you to stay indoors, stay in your homes for the time being. we are asking businesses in those areas to please cooperate and not open today until we can provide further guidance and information. so again, to repeat, to the residents of watertown, newton, belmont, cambridge, and the austin brighton neighborhoods of boston, we're asking you to stay home, stay indoors.

we're asking businesses not to open. we're asking people not to congregate outside. we're asking people not to go to mass transit. and we are hopeful that as the day proceeds that we can provide further guidance, that we'll be able to open portions of the system and be able to ease these restrictions, but we are imposing that now. let me just ask chief, for the town of watertown, is there anything additional -- >> i just want to speak to the town of watertown. we need your help now. we need everybody to shelter in place. no traffic will be allowed in or out. no businesses will be allowed to be opened. the watertown community has always stood strong. we need them to do that today. >> before we take any questions, i need to be clear about this. this situation is grave. we are here to protect public safety in these neighborhoods

here in watertown right now. i know that there's national media here from all over the country. i know you have a lot of questions about who these folks are, where they're from. there will be plenty of time to deal with that over the ensuing hours. right now we have to deal with this here. we appreciate your patience. we believe these are the same individuals that were responsible for the bombing on monday at the boston marathon. we believe that they're responsible for the death of an m.i.t. police officer and the shooting of an mbta police officer. this is a very serious situation that we're dealing with. we would appreciate your cooperation. we'll do the best we can to keep you apprised as to how that develops here this morning, but we can't answer every single question about this investigation at this particular point in time. thank you very much. >> we'll be back. we'll let you know as much as possible prior to the next briefing. >> all right. you just heard a plea from the police chief in watertown, massachusetts, as well as law

enforcement authorities to stay indoors. businesses should stay closed. do not use mass transits. do not drive in the streets. unprecedented but perhaps the only thing they can do to try and find the second suspect. let's go to nbc's pete williams with more on this. pete?

authorities have not released any names. they say they're still trying to positively identify them. they believe that they've been in the u.s. for about a year, that they have some foreign military experience, and the boston police commissioner, ed david, said a short time ago of the man with the white hat, that he believes this man to be a terrorist who has come here to kill people, is the way he put it, mika.

>> okay. willie geist joins us. willie, jump in. >> pete, it's willie. as you say, these two suspects believed to have been here as long as a year. do we know in what capacity? were they students? do we know anything about why they've been here? >> presumably students. we don't have the answer to that. they're still trying to tentatively -- they're still waiting to get the positive identification. we don't know the precise nature of what the visa was or how they entered the u.s. >> as you say, a remarkable lockdown here. we're talking about the commuter rail, the t, the subway there, buses. that's people getting in and out of downtown boston. and the western suburbs essentially locked down. nobody allowed outside. newton, watertown, belmont, waltham, cambridge, alton, brighton. all in a state of lockdown. pete, do they have any leads at this point? a guy gets into a car and drives away. they said he fled on foot.

did they pursue him at that point? >> he did get away and they were trying to find him. they now believe they know the building where he is. that's their belief. they're not positive about it, but they think they know where he is. because they're not sure, that's why the community is on lockdown. >> so pete, the little that we know, the ied strapped to the suspect who perished, his body, the grenades and explosives that were tossed out of the car window, it seems that this isn't just homemade in the last minute, in the past few weeks, that this is planned. is there any possibility there could be others involved given the amount of explosives that they had? >> possibility, certainly, but no reason to think so that i've heard of. that's obviously one of the things they'll now try to pursue once they get this situation in watertown under control. they will now try to backtrack, look at these men's background. i've heard nothing to indicate others are involved. >> pete, just following your

chronology here. robbing the 7-eleven seems to be the moment that set this off. >> yes. >> did the fbi or any local law enforcement have a lead on them between the time they released the photographs and that robbery at 7-eleven? in other words, had they gotten on to their trail, or was it that event that set this all off? >> well, i think two answers to that, willie. one is this whole sequence of events starts because these men took this action tonight. >> right. >> not because the fbi was moving in on them. now, having said that, their names were among people that the fbi was trying to find. there was interest in them. so they were sort of on the fbi's radar. these names are not -- the fact we know as much as we do about them is because they'd already begun to consider them possible suspects. there were others, but these were certainly on their list. >> nbc's pete williams. we'll be checking back with you later.

thank you very much. willie geist, this has been an incredible night of astonishing breaking news as the two suspects, which seem to elude police and law enforcement authorities in the moments after the double bombing at the boston marathon, now with all the pictures and the video that they were able to put together, they were able to hone in on these two guys and even hone in on video that showed them watching after the initial bombing attack in boston, which shows just the brazen, sick, atrociousness of their approach to this, that this is -- these guys were on a rampage to do much more. they were armed, dangerous, and you know, the night didn't end without them killing or maiming more people. >> there can be no question now that they had further intent based on what they had with them last night. according to pete's reporting and others, they were throwing explosive devices out the

vehicles during the chases. the suspect who eventually died wearing an ied on his body. we don't know where they were headed, what they were about to do. it looks like that was fwathwar. again, there's still one suspect, the gentleman in the white hat, on the run. the western suburbs of boston essentially locked down. the mbta is shutting down until further notice. it's buses, subways, commuter rail. that's people coming in and out this morning of boston. this city is locked down. this is incredibly unusual. this is remarkable. that tells you how dangerous they think this remaining suspect is. >> law enforcement officials just had a news conference a few minutes ago telling people to keep their businesses closed, to stay in their homes, not to drive in the streets, not to use mass transit. then the police chief got to the microphone, and it was a desperate plea. please, please, watertown, just stay home today, lock down, don't talk to anyone unless it's a cop. the fear in watertown is

palpable. our prayers are certainly with the people in watertown and the surrounding areas. and our prayers they find this guy as soon as possible. let's go now to nbc news national security analyst michael leiter, who's in washington. michael, we've been gathering information throughout the night. we want to be careful. having said that, it's fairly clear that there were two men on the run who were highly armed and dangerous. one is down. that man had an ied strapped to his body. what are the possibilities that people ought to consider in the watertown area and surrounding towns when they think about this guy on the run in their midst? >> well, as willie said, the fact they're shutting down the entire metropolitan boston transit authority and stopping cars in movement into and out of watertown is almost unprecedented. certainly is in boston. we've done this sort of thing when we had the attempted times square bombing around times square. obviously, on 9/11, shutting down the streets into and out of

manhattan. but this really does give a sense of how dangerous the police and the fbi think these individuals are. so in that sense, just be meticulous in following instructions. stay away, stay in your houses. i think this highlights why the fbi was so upset with the leak of information and inappropriate reporting. because they understood how dynamic this was going to continue to be. you know, this is now focused on watertown. over the next 12, 24 hours, there will be other locations where the police find out where they were, other sites searched. so this is very dynamic. >> michael, it's willie. tell us about what's happening right now for law enforcement. they have one suspect dead but one who, based on what he's done in the past, still has to be deemed incredibly dangerous based on the bombings for which he's a suspect on monday and based on what they were carrying in that vehicle with them a few

hours ago last night. what does law enforcement suspect he's doing right now? >> first of all, they're trying to get the facts clear as well. reporting from these scenes is going to be incredibly garbled. they're going to do as much forensic analysis as they can. they're going to track the individual. if, in fact, he was international, a student visa, they're going to search records against other people who came into the country when he did. they're going to be doing the same thing with the other individual to try to identify him. they'll go back and look for communications between these two. so this is another threat that they're pulling. they're going to pull on all of these threads over the next several hours. >> all right. it's just about the top of the hour. 6:00 on the east coast. it's been an astonishing night on the east coast. willie geist is here with me in new york as we cover the reports of explosions and a massive gunfight with two men in watertown, massachusetts. it's evolved into a full-on man hunt. it's all